Study on pull-out mechanical characteristics and critical anchorage length of prestressed anchor bolts
Compared with the non-prestressed bolt,the prestressed bolt shows special supporting mechanical characteristics after being pulled out.In order to deeply investigate this characteristic of the prestressed bolt,the full-scale indoor experiments and theoretical analysis were used to study the mechanical response of the prestressed bolt after being loaded,and the supporting mechanical characteristics of the prestressed bolt and its mechanism were further understood,which further extended the active support theory of the prestressed bolt.Additionally,from the perspective of optimizing the support performance of the anchorage system,the numerical calculation method for the critical anchorage length of the prestressed resin bolt was proposed based on the secondary development mean.The results showed that:(1)After the prestress was applied,the shape of the load-displacement curve of the bolt changed obviously,the support stiffness increased in the early stage,and the load mutation point appeared at the same time.With the increase of prestress application value,the load value at the mutation point increased from 17.3 kN to 54.6 kN;(2)The prestressed bolt exhibited an initial increase in stiffness after being subjected to the tensile load,followed by an increase in strength in support mechanics,quickly providing the larger bearing capacity in the early stage of support and effectively improving the ability of the anchorage system to control the deformation of the surrounding rock;(3)The established numerical analysis model well reproduced the mechanical response of the anchorage system under the tensile load,based on which the peak bearing capacities of the anchorage system under different anchorage length conditions had been analyzed,and the critical anchorage length of the resin bolt under this experimental condition had been determined to be 44 cm.The relevant research results have guiding significance for understanding the support mechanical characteristics and parameter design of prestressed anchorage systems.
rock mechanicsprestressboltpulling-out experimentanchorage lengthsupport mechanics
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